Avoid iterating every operand of an instruction in StrongPHIElimination, since

we are only interested in the defs when discovering interferences.

This is a 28% speedup running StrongPHIElimination on 403.gcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122596 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index c1a76a6193a8c24114916826d7b98c94d3e0c47c..f84fdbe5bc2c45990319825903d7f6018eb76e4e 100644 (file)
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -471,10 +471,9 @@ StrongPHIElimination::SplitInterferencesForBasicBlock(
     DenseMap<unsigned, unsigned>& ImmediateDominatingParent) {
   for (MachineBasicBlock::iterator BBI = MBB.begin(), BBE = MBB.end();
   BBI != BBE; ++BBI) {
-    for (unsigned i = 0, e = BBI->getNumOperands(); i != e; ++i) {
-      MachineOperand& MO = BBI->getOperand(i);
-      if (!MO.isReg() || !MO.isDef())
-        continue;
+    for (MachineInstr::const_mop_iterator I = BBI->operands_begin(),
+         E = BBI->operands_end(); I != E && I->isReg() && I->isDef(); ++I) {
+      const MachineOperand& MO = *I;
 
       unsigned DestReg = MO.getReg();
       if (!DestReg || !TargetRegisterInfo::isVirtualRegister(DestReg))